Selection in Agrobacterium-mediated transformation Which selectable marker enzymes are routinely used to recover plant cells transformed by Agrobacterium?

Introduction / Context:
Selectable markers enable researchers to isolate the relatively few plant cells that acquire and express T-DNA after Agrobacterium infection. Understanding common marker enzymes and antibiotics is fundamental for designing transformation experiments and interpreting regeneration results.

Given Data / Assumptions:

• Agrobacterium delivers T-DNA harboring a selectable marker gene into plant cells.
• Markers typically confer antibiotic resistance that permits growth on selective media.
• Different crops and protocols favor different antibiotic/marker combinations.

Concept / Approach:
Widely used markers include neomycin phosphotransferase II (NPTII; kanamycin/G418 resistance) and hygromycin phosphotransferase (HPT; hygromycin resistance). Streptomycin/spectinomycin resistance cassettes are also used in some systems. The best choice depends on plant sensitivity, background tissue responses, and regulatory considerations.

Step-by-Step Solution:

Verification / Alternative check:
Transformation protocols across tobacco, tomato, rice, and Arabidopsis document successful selections using kanamycin or hygromycin; some use streptomycin/spectinomycin in plastid or nuclear selection schemes.

Why Other Options Are Wrong:

• NPTII or HPT alone: each is valid but not exclusive.
• Streptomycin phosphotransferase alone: valid in some cases but not the only standard.
• lacZ alone: a reporter, not a robust selectable marker in plants.

Common Pitfalls:
Using antibiotic levels that either fail to suppress escapes (too low) or kill regenerable transformants (too high). Always empirically determine minimal lethal concentrations for the target tissue.

Final Answer:
Any of the above, depending on the vector and plant species